02 Basic concepts

Question 1

How is the endocrine system different from the nervous

Answer 1

endocrine is anatomically discontinuous

both:

• major communications systems in the body
• integrate stimuli and responses to changes in external and internal environment
• crucial to coordinated functions of highly differentiated cells

Question 2

How does the endocrine system broadcast hormonal messages

Answer 2

to all cells via secretion into blood and extracellular fluid

• slow and diffuse
• one gland potentially affects many or all body tissues

Question 3

What are general principles of endocrine gland organization

Answer 3

Ductless
Highly vascular
Functional secretory cells are usually epithelial

Question 4

What are the three types of endocrine organ arrangements

Answer 4

• Discrete glands (thyroid)
• Endocrine components of other organs (pancreas, gonads, ovaries, testis)
• Scattered cells throughout other organs (C cells in thyroid)

Question 5

What are some basic characteristics of hormones

Answer 5

May have more than one target
active in low concentrations
more than one hormone may affect a target
May have same actions in more than one tissue, or opposite actions in two tissues

Question 6

What are the 3 classes of hormones

Answer 6

Amino acids
Steroids
Proteins

Question 7

What are characteriestics and examples of steroid hormones

Answer 7

• originate from a cholesterol precursor
• organs: ovaries, testis, adrenal cortex
• lipid soluble; bind to receptors inside the target cell

mineralcorticoids, glucocorticoids, testosterone, and estradiol

Question 8

What are characteriestics and examples of protein hormones

Answer 8

• name indicates chemical structure
• wide variety of molecule sizes
• organs: anterior pituitary, thyroid, parathyroid, pancreas
• NOT lipid soluble; bind to surface receptors of the target cell

Insulin, prolactin, ADH, oxytocin, and parathormone

Question 9

What are characteristics and examples of amino acid hormones (analogues and derivatives)

Answer 9

• name indicates chemical structure
• organs: thyroid, adrenal medulla
• most not lipid soluble (exception thyroid); bind to receptors on the surface of target cell

tyrosine derivatives = catecholamines (dopamine, epinephrine, norepinephrine) & thyroid hormones (Thyroxine T4, Triiodothyronine T3)

Question 10

How are steroid hormones produced/stored

Answer 10

produced on demand and not stored

Question 11

What types of organelles do steroid producing cells have the most of

Answer 11

SER, golgi

Question 12

Where are amino acids, peptides, glycoproteins and protein hormones stored

Answer 12

Granules

ex: insulin in pancreas

Question 13

What types of organelle do protein hormone producing cells have high levels of

Answer 13

RER

Question 14

What type of cells do hormones have an affect on

Answer 14

target cells

Question 15

Why do target cells respond to hormone

Answer 15

The cell has a receptor for the hormone

Question 16

What are the two types of hormone receptors

Answer 16

Membrane receptors

Cytoplasmic receptors

Question 17

What type of receptors do steroid hormones target

Answer 17

cytoplasmic/nuclear receptors

Question 18

How does a steroid hormone change cell function

Answer 18

1) Bind to nuclear or cytoplasmic receptor
2) dimerizes
3) receptor hormone complex binds specific DNA sequences
4) Directly alters gene expression at the response element or promoter
5) produces a protein that elicits a biological response

Question 19

How does hormonal action by plasma membrane receptors work

Answer 19

Hormone is 1st messenger
G proteins in cell membrane are activated
2nd messenger causes intracelluar change; may be cAMP, cGMP, Ca++

• used by hormones that cannot diffuse through the - -
  plasma membrane: amines, peptides, proteins
• hormone does NOT directly alter gene expression

Question 20

name the endocrine glands of animals (9)

Answer 20

hypothalamus
pineal gland
pituitary gland
thyroid gland
parathyroid gland
adrenal gland
pancreas
ovary
testes

Question 21

how does the nervous system send signals

Answer 21

• exerts point to point control through nerves
• electrical in nature
• fast

Question 22

what are the principle functions of the endocrine system

Answer 22

• maintains homeostasis
• integrations and regulation of growth, metabolism, and development
• control, maintenance and instigation of sexual reproduction (including gametogenesis, fertilization, fetal growth, and development, and nourishment of the the newborn)

Question 23

what are the 3 methods of cell communication between cells? Define them.

Answer 23

endocrine: hormone secreted into blood bonds distant target cells
paracrine: hormone acts locally by diffusing from its source to target cells in the neighborhood
autocrine: hormone acts on same cell that produced it

Question 24

patterns of hormone secretion

Answer 24

some hormones secreted tonically (all the time); some secreted episodically (pulses)

frequency and amplitude of pulses vary in response to stimuli

diurnal (day, year, etc) and annual rhythms

Question 25

what is the pattern of secretion of circulating cortisol

Answer 25

diurnal
strong pulse at 8am
moderate pulses at 1pm, 8pm, 6am

Question 26

what is the pattern of secretion of gonadotropin in males and females

Answer 26

varies over a lifespan
increases during fetal development
childhood FSH > LH
puberty slowly increasing
sinusoidal rhythm during adult reproductive period (LH > FSH)
greater increase in females as they age but both increase (FSH > LH)

Question 27

what are the control mechanisms used to regulate hormones

Answer 27

external stimuli (fright, cold, light cues)
internal stimuli (blood sugar levels, hormonal signals from another gland)
feedback loops

Question 28

what disease is an example of the critical importantance of receptors

Answer 28

Type II Diabetes

caused by a lack of response NOT lack of hormone

Question 29

How does hormonal action through intracellular receptors work?

Answer 29

characteristic of steroid and thyroid hormones
steroid hormones diffuse through plasma membrane
bind to nuclear (or sometimes cytoplasmic) receptor
receptor-hormone complex binds specific DNA sequences
directly alters gene expression
new mRNA and proteins made
new proteins change cell function